The present invention relates to a carburetor for internal combustion engines and more particularly to a carburetor for metering fuel in response to varying atmospheric and load conditions.
In the automotive art, carburetors of various types have been proposed for controlling delivery of fuel and air to the cylinders of an internal combustion engine. While the various devices have differed widely in construction, the basic functions of metering and atomizing the fuel and then adjusting the rate at which the fuel air mixture is made available for combustion are common. In addition, metering of fuel has typically been accomplished by a needle valve operated by a float which monitors fluid level in a fuel reservoir or bowl. The use of a needle valve in which a tapered needle is received within a circular orifice makes precise metering difficult to achieve since the area of the opening does not vary uniformly in direct proportion to movement of the needle. In addition, the float depends upon gravity and must be free to move within the bowl, so it becomes ineffective when the carburetor is tilted sharply or bounced. As a result flooding of the carburetor occurs frequently in off-road vehicles, such as motorcycles, ski mobiles, motor boats, four wheel drive vehicles, etc., when the vehicle is turned sharply or driven over rough or sharply inclined terrain.
In previously known carburetors, fuel has been metered according to a predetermined schedule, so that variations in atmospheric conditions have resulted in fluctuations in the fuel-to-air ratio. Thus, the engine is operated at other than optimum fuel-to-air ratios much of the time.